The body control module (BCM) monitors the outside air temperature sensor to display outside air temperature. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The BCM applies 5 volts to an internal input resistor that is connected to the signal circuits of the outside air temperature sensor. The BCM provides the ground to the outside air temperature sensor through the low reference circuit. When the outside air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the outside air temperatures are hot; the resistance of the sensor is low and the voltage signal is low. The BCM converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the instrument panel cluster (IPC).

Ignition ON.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Ambient Air Temp. Sensor parameter, the reading should be between 0.1 and 4.9 volts and change with temperature.

1. Ignition OFF, disconnect the harness connector at the outside air temperature sensor.
2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

3. Ignition ON, verify the scan tool Ambient Air Temp. Sensor parameter is greater than 4.9 volts.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Ambient Air Temp. Sensor parameter is less than 0.1 volt.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the outside air temperature sensor.

1. A thermometer can be used to test the sensor off the vehicle in warn and or cold water. Sensor Resistance Table for this test.
2. Test the evaporator air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
3. Compare the readings with the Temperature VS Resistance table and verify that the resistance is within 5 percent of the specification.

⇒	If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.